I was thinking that in might be helpful if the topic timeline prominently indicated where “x day/month/year later” posts show up. Right now the topic timeline is very simple, which of course has its benefits. But I think adding hashmarks or similar to show when a topic was necro’d (already denoted at the specific posts themselves where it says thing like “15 days later”) would be useful. Necros should be rare enough for most topics that it’s not likely to become overwhelming most of the time. And when they are common relative to the total number of posts in the topic, it also likely means there aren’t many posts to begin with (meaning they’d still be spaced out well on the timeline), so it probably still wouldn’t clutter the topic timeline that much.